Pushbutton switch



P 1962 J. E. SORENG 3,054,879

PUSHBUTTON SWITCH Filed Jan. 20, 1960 INVENTOR.

John E 50119225 United States Patent Ofilice 3,054,879 Patented Sept.18, 1962 This invention relates to pushbutton switches, which have avariety of applications. Thus, such switches may be employed in variouscontrol circuits, such as the starter circuit for an internal combustionengine.

One object of the present invention is to provide a pushbutton switchwhich is extremely dependable in operation, yet is easy to manufactureand low in cost.

A further object is to provide a new and improved pushbutton switch inwhich the movable contact element automatically aligns itself with thestationary contact element, so as to assure good electrical contacttherebetween.

Another object is to provide a new and improved pushbutton switch whichis arranged so that there is a wiping action between the movable contactand the fixed contacts, so that the contacts are automatically kept freefrom dirt or other deposits which might impair the effectiveness of theelectrical contact between the contact elements.

A further object is to provide a pushbutton switch in which the movablecontact member is freely rotatable, so that it will tend to presentfresh contact areas to the stationary contacts as the switch is usedrepeatedly.

Further objects and advantages of the present invention will appear fromthe following description, taken with the accompanying drawings, inwhich:

FIG. 1 is a side elevational view of a pushbutton switch to be describedas an illustrative embodiment of the present invention, the View beingdrawn to show the manner in which the switch may be mounted on a panelby means of a mounting plate, the panel and the mounting plate beingshown in section.

FIGS. 2 and 3 are rear and front elevational views, respectively, of thepushbutton switch itself.

FIG. 4 is an enlarged sectional View, taken generally along a line 44 inFIG. 3.

FIGS. 5 and 6 are cross-sectional views, taken generally along lines 5-5and 66 in FIG. 4.

It will be seen that the drawings illustrate a pushbutton switch 10which comprises a plurality of stationary contact points 12, adapted tobe bridged or connected together by a movable contactor 14. As shown,the stationary contact points 12 are mounted on a supporting member orplate 16 which is made of insulating material. It will be seen that theplate 16 is in the form of a circular disk. The contacts 12 may comprisethe head portions of rivets 18 which extend through spaced holes 20 inthe insulating plate 16. Terminals 22 in the form of angular lugs may besecured to the rear side of the insulating plate 16 by the rivets 18.Thus, each terminal lug 22 has one flange 24 which lies flat against theplate 16 and is mounted on the rear portion of the rivet 18, and anotherflange 26 which projects rearwardly, at right angles to the plate 16. Itwill be seen that the contact members 12 are substantially conical inshape. They project forwardly from the plate 16 for engagement by themovable contactor 14.

It will be seen that the contactor 14 is mounted on a movable supportingmember in the form of a flexible boot 2%. The front portion of the boot28 is formed into a pushbutton 30 which may be engaged and pushedrearwardly by one finger or the thumb of the user. Annular grooves 31are formed into the front of the pushbutton 30 to provide a non-slipsurface.

The boot 23 has a bellows portion 32 which supports the pushbuttonportion 30 so that it may readily be pushed inwardly toward the fixedcontacts 12. As shown, the bellows portion 32 comprises a generallycylindrical wall 34 which is somewhat larger in diameter than thepushbutton portion 30. The cylindrical wall 34 is connected to thepushbutton portion 30 by an annular flange 36 which is generallyL-shaped in cross-section. Thus, the flange 36 has a pair of angularlyrelated legs 38 and 40. As shown, the leg 38 extends inwardly .in agenerally radial direction from the cylindrical wall 34, and then joinswith the leg 40, which extends to the edge portion of the pushbutton 30,in a direction generally parallel to the cylindrical axis of the wall34. The leg 38 of the flange 36 actually angles rearwardly to someextent, so as to impart great flexibility to the boot 28.

The boot 28 is preferably made of rubber, or some other rubber-likematerial which is flexible, resilient and relatively soft. Theresilience of the boot 28 restores it to its original shape when thepushbutton 30 is released. Thus, the boot 28 provides its own springaction.

In this case, the boot 28 is formed with an enlarged annular flange 42which retains the supporting plate 16. As shown, the flange 42 isgenerally 'C-shaped in crosssection. Thus, the flange 42 has three legs44, 46 and 48. The leg 44 extends outwardly from the rear end of thecylindrical wall 34, and then joins with the leg 46 which is generallycylindrical and thus extends generally parallel to the axis of thesupporting disk 16, along the outer edge thereof. The leg 48 extendsinwardly along the rear surface of the disk 16. Thus, the C- shapedflange 46 forms an internal annular groove 50 which is adapted toreceive the edge portion of the insulating disk 16. By flexing theC-shaped flange 42, the disk 16 may readily be inserted into the groove50 or removed therefrom.

In the illustrated construction, the movable contactor 14 comprises adished metal member which has a skirt portion 52 angling outwardly froma flat central disk portion 54. The contactor 14 is mounted on therubber boot 28 by means of a rivet 56 having a front head portion 58which is retained in a generally T-shaped recess 60 formed in thepushbutton portion 30 of the rubber boot 28. The rivet 56 has a reducedportion 62 which extends loosely through an opening 64 in the centraldisk-shaped portion 54 of the contactor 14. At its extreme rear end, therivet 56 has a head 66 which retains the contactor 14 on the rivet.Because of the loose fit between the reduced portion 62 and the opening64, the contactor 14 is free to rotate on the rivet. Moreover, thecontactor 14 is free to swing or rock to a substantial extent on therear portion of the rivet.

It will be seen that the skirt 52 of the contactor 14 is frusto-conicalin shape and is of sufficient size to be received over the stationarycontact points 12. Thus, the contact points 12 are adapted to be engagedby the inner surface of the frusto-conical skirt 52, at diametricallyopposite points. The angle of inclination or taper of the frusto-conicalskirt 52 corresponds generally to the angle at which the conical contactpoints 12 taper. Accordingly, the inside of the frusto-conical skirt isadapted to engage each of the conical contact points 12 along a definiteline of contact.

From FIG. 1 it will be seen that the switch 10 is adapted to be mountedagainst a panel or wall 70, by means of a clamping or mounting plate 72.In this case, the panel 7 (l is formed with an opening 74, through whichthe terminals 22 project in a rearward direction. The mounting plate 72is secured to the panel 70 by means of a pair of bolts or otherfasteners 76.

As shown, the cylindrical portion 34 of the rubber spacers boot 28projects forwardly through an opening '78 in the mounting plate 72. Aforwardly projecting annular flange 80 is formed on the mounting plate'72 around the opening 78. It will be seen that the flange all isgenerally L-shaped in cross-section. Thus, the flange 80 has acylindrical portion 82 which projects forwardly from the mounting plate72. In addition, the flange 80 has an inwardly projecting radial portion84- connected to the front end of the cylindrical portion 82. The radialflange portion 84 engages the front of the enlarged rear portion 42 ofthe boot 28 and is adapted to clamp the enlarged rear portion againstthe panel 79. Thus, the inwardly projecting flange portion 48 of theboot 28 is firmly held against the panel '70 around the opening 74. Thecylindrical portion 82 of the flange St! extends around the rearcylindrical portion 46 of the boot 2%.

Normally, the contactor 14 is spaced forwardly from the fixed contactpoints 12, as shown in full lines in PEG. 4. The switch it) is operatedby pushing the pushbutton member 30 rearwardly with the thumb or onefinger of the operators hand. This brings the inside of thefrusto-conical contactor 14- into contact with the outer surfaces of thecontact points 12, as shown in broken lines in FIG. 4. There is adefinite wiping action between the contacting surfaces, when thepushbutton switch is operated due to the self-aligning movement of thecontacting surfaces. This wiping action keeps the contacting surfacesclean and obviates any possibility of faulty electrical contact due tothe accumulation of dirt or other deposits on the contacting surfaces.The frusto-conical shape of the contactor 14 causes it to align itselfautomatically with the conical contours of the contact points 12.Aligning movement of the contactor 14 is readily possible, because ofthe loose connection between the contactor and the supporting rivet 56.Inasmuch as the contactor '14 is freely rotatable on the rivet, thecontactor will tend to rotate to various positions due to normal use ofthe switch and normal conditions of vibration under which the switch isused. Thus, the contactor 14 will constantly be presenting new contactsurfaces to t e stationary contact points 12. Accordingly, the highefliciency of the pushbutton switch is maintained over an extremely longlife span. Of course, the rubber boot 23 excludes dust and other foreignmaterial from the coutacting surfaces. At the same time, the rubber bootprovides a spring action which disengages the contactor 14 from thecontact points 12 when the pushbutton member 30 is released.

Various modifications, alternative constructions and equivalents may beemployed without departing from the true spirit and scope of theinvention, as exemplified in the foregoing description and defined inthe following claims.

I claim:

1. A pushbutton switch, comprising, in combination, a generally circularinsulating plate having a pair of generally conical contact pointsmounted thereon and projecting forwardly from said plate, a pair ofterminals connected to said contact points and mounted on the rear sideof said plate, a hollow flexible boot made of rubberlike material andextending from the front side of said plate, said boot having apushbutton portion disposed centrally on said rubber boot and at thefront end thereof, a mounting stud mounted in the rear side of saidpushbutton member and extending rearwardly therefrom inside said boot,and a movable sheet metal contactor loosely mounted on said mountingstud and freely rotatable and swingable thereon, said contactor beinggenerally frusto-conical and being receivable over said generallyconical contact points to establish an electrical circuit therebetween,said contactor tapering at an angle corresponding to the angle of taperof said contact points to afford wiping contact between said contactpoints and said contactor, said contactor being self-aligning with saidcontact points and being rotatable to present new contacting surfaces tosaid contact points.

2. In a. switch, the combination comprising an insulating plate, aplurality of generally conical contacts projecting forwardly from saidplate, a hollow flexible resilient boot connected to the front of saidplate, and a thin metal contactor mounted on the inside of said boot andmovable rearwardly into engagement with said contacts to establish anelectrical circuit therebetween, said boot biasing said contactorforwardly away from said contacts, said boot having means on the insidethereof supporting said contactor for free rotation and loose swingingmovement relative thereto so that said contactor will be self-aligningwith said contacts, said contactor having an inner frusto-conical wallflaring toward said contacts and engageable therewith with a wipingaction.

3. In a switch, the combination comprising a substantially circularinsulating plate, a pair of spaced rivets mounted in said plate andhaving heads on the front side thereof in the form of generally conicalcontact points projecting forwardly from said plate, a pair of terminalsmounted on said rivets and extending from the rear side of said plate, ahollow generally cup-shaped boot mounted on said plate and extendingforwardly therefrom, said boot being of flexible resilient rubberlikematerial, said boot having a front centrally disposed pushbuttonportion, a stud mounted in said pushbutton portion and projectingrearwardly therefrom into the interior of said boot, a sheet metalcontactor having an opening therein loosely mounted on said stud, saidcontactor being freely rotatable and rockable relative to said stud,said contactor being movable rearwardly against said contact points toestablish an electrical circuit therebetween, said boot normally biasingsaid contactor forwardly out of engagement with said contact points,said contactor having a flaring skirt-like wall with a generallyfrusto-conical inner surface engageable with said contact points with awiping action, the flaring angle of said contactor wall correspondinggenerally with the conical angle of said contact points, said contactpoints being engageable with said wall at diametrically oppositelocations thereon.

4. A pushbutton switch, comprising, in combination, an insulating platehaving a pair of generally conical contact points mounted thereon andprojecting forwardly from said plate, a pair of terminals connected tosaid contact points and mounted on the rear side of said plate, a hollowflexible boot made of rubber-like material and extending from the frontside of said plate, said boot having a pushbutton portion disposedcentrally on said rubber boot and at the front end thereof, a mountingstud mounted in the rear side of said pushbutton member and extendingrearwardly therefrom inside said boot, and a movable sheet metalcontactor mounted on said mounting stud, said contactor being generallyfrustoconical and being receivable over said generally conical contactpoints to establish an electrical circuit therebetween, said contractortapering at an angle corresponding to the angle of taper of said contactpoints to afford wiping contact between said contact points and theinside of said contactor.

References Cited in the file of this patent UNITED STATES PATENTS1,717,057 Meuer June 11, 1929 2,409,483 Gandelot Oct. 15, 1946 2,444,552Brantingson July 6, 1948

